The National Institute for Environmental Health Sciences and the National Cancer Institute propose to continue support for studies of the environmental impact on the etiology of breast cancer, especially through understanding the role of the environment on puberty and early development. As part of this initiative, the Breast Cancer and the Environment Program (BCERP), they will support the continuation of a cohort of young girls through puberty and into adolescence to assess a broad range of environmental factors on pubertal outcomes and intermediate markers of breast cancer risk. The investigators herein propose to be the Coordinating Center for the BCERP. Their specific aims will be: 1) To act as a central repository and clearinghouse for cross-site data from the epidemiologic study of girls early development through puberty and into adolescence; be responsible for the entry, coordination, monitoring, and harmonization of all data collected for cross-site analysis, basic analytic support and facilitation of data sharing and cross-site activities;. 2) To organize meetings and regular conference calls for all organizational entities within the BCERP, including annual business and scientific meetings and meetings to promote transdisciplinary science and other functions required of the BCERP; 3) To facilitate the monthly meetings and other activities of the BCERP Steering Committee; 4) To compile for the Steering Committee regular reports of research activities and accomplishments of the epidemiologic studies; facilitate the NIH oversight and administration of the BCERP and the Pilot Project/Opportunity Fund; and, 5) To support the operations of an expert Working Group on Breast Cancer and the Environment. The investigators believe that they have several significant strengths to be considered in this application, which include; highly experienced and relevant leadership; the highly experienced and well established San Francisco Coordinating Center at the University of California San Francisco (UCSF); and an organizational structure that takes advantage of their past experience of seven years in the Breast Cancer and the Environment Research Centers, which was the first phase of this research initiative.